I'm looking for a portable system for HD650/800. I was considering HIFIMAN 901, but it's out of stock in Japan for quite a while. Besides, as a portable player, it seems like 901 is still not very enough for HD650.   I was suggested to try HIFI-M8, but still, it's not available in both Japan...

As my first question of the headphones in my entire life, I am really seek inputs for the performance of using Hifiman 901 directly with HD 650 or HD 800.   I have already searched a lot websites for this question. From "not a chance" to "pretty damn good", I got almost every kind of reviews...